The standardization of the WPAN (Wireless Personal Area Network) standards is being made as the 802.15 standards under the IEEE 802 Committee. A high-speed short-range communication method called UWB (Ultra Wide Band) is one of the communication methods adopted in the WPAN. According to the UWB specifications, it permits data rates as high as 110 Mbps at a communication distance of 10 meters in radius and 480 Mbps at a communication distance of 3 meters in radius.
In recent years, a notebook type personal computer (hereinafter, referred to as a notebook PC) allows connections with digital consumer electronics, mobile apparatuses or peripheral devices by using a wireless shared platform in compliance with the UWB. The wireless shared platform is configured by a UWB physical layer and a UWB-MAC layer. Moreover, in order for the UWB wireless shared platform to be shared with various applications or protocols such as the wireless USB (WUSB: Wireless Universal Serial Bus) or the wireless IEEE 1394, a convergence layer is defined above the UWB-MAC layer.
As one of the peripheral devices of the notebook PC, there is known a function expansion device called a port replicator. The port replicator is provided with connection terminals such as serial ports, parallel ports, and ETHERNET connectors, and the port replicator may be placed on a desk so that peripheral devices less frequently used may preliminarily be connected thereto. Moreover, the main body of a notebook PC has been designed to be small in size and lightweight in order to be used in a mobile environment. On the other hand, in an office environment, the notebook PC is connected to the port replicator so that functions equivalent to a desktop computer can be used.
Japanese Patent Application Laid-Open No. 2001-167038, discloses a technique in which, when a mechanical lock mechanism is not present between a docking station and a PC, a device driver is unloaded before entering into a suspend or hibernation state so that the PC can be solely operated even when the PC is undocked from the docking station during the suspend state.
Japanese Patent Application Laid-Open No. 2000-047763, discloses a technique in which in order to solve a problem that prevents a computer from resuming its operation when a resume function is performed after a CD-ROM is removed during a suspend state, the connection state of the CD-ROM is checked when performing the resume function to thereby control subsequent accesses to the CD-ROM.
Japanese Patent Application Laid-Open No. 2004-282722 discloses a technique that notifies a user of a communication state between a docking station and a computer by means of an LED's lighting state. Japanese Patent Application Laid-Open No. 2006-301770, discloses a method that interrupts a safety remove operation when accesses are continuously made to a docking station and displays a message indicating that the docking station cannot be removed.
In recent years, a wireless port replicator or a wireless docking station (hereinafter collectively referred to as WPR) capable of connecting a port replicator and a notebook PC by using a wireless platform of UWB has been developed. The WPR may be connected to a magnetic disc device (hereinafter referred to as HDD) by wire. A user reads files from the HDD to edit them or newly creates files with the notebook PC to write them into the HDD. The user may sometimes carry the notebook PC to be away from the WPR before the files are written to the HDD or the files are completely read from the HDD.
On one hand, connecting the notebook PC and the port replicator by wireless frees a user from burdensome physical connecting operations to thereby provide agreeable working environment. On the other hand, the user becomes less aware of the state where the notebook PC is connected to the WPR. As a result, there is increasing possibility of occurrence of a so-called surprise removal wherein the notebook PC is carried outside a wireless communication zone before data being edited is saved or files being read are completely read. Although the UWB communication distance is about 10 meters in radius, when the distance between the notebook PC and the WPR exceeds the UWB communication distance, the wireless communication path between the notebook PC and the HDD may be cut off. Therefore, since it is difficult to obtain the data under reading or store it in the HDD at the moving destination, there may be a case where the data is lost due to operation errors with respect to the edited data.
When the notebook PC and the port replicator are connected by wire, it is easy to recognize the disconnection from the HDD when the port replicator is ejected, and it can be expected that the user will preliminarily save the data being edited or to confirm that the data being read has been completely read. Moreover, attachment/removal can be followed by operating an eject button, which is made to be impossible to unlock the eject button, which is normally mechanically locked, before the ejection operation is completed.
However, when the notebook PC and the port replicator are connected wirelessly, the same measures taken when connected by wire cannot be taken wirelessly. Moreover, the surprise removal problem occurs when the resume function is performed after the notebook PC is carried outside of the wireless communication zone after transitioning to the suspend or hibernation state in a state of being connected to the WPR.
Therefore, a need has been recognized for providing an access method for a portable computer capable of preventing the occurrence of a surprise removal with respect to a wirelessly connected external storage device.